On Nutrition

DEAR DR. BLONZ: I am aware of the dangers of trans fats, but I am also concerned that some foods, like shortening, still use hydrogenated fats. Are these any better than the trans fats in partially hydrogenated shortening? One brand now uses “fully hydrogenated,” rather than partially. Is that better or worse for cooking? -- F.C., San Jose, California

DEAR F.C.: The quick explanation is that a fully hydrogenated shortening does not have any trans fats. Imagine a road stretching between an unprocessed, unsaturated liquid vegetable oil and a solid block of fully hydrogenated fat. On this road, partially hydrogenated fats are somewhere in the middle. The important issue here is that the process of partial hydrogenation is what creates trans fatty acids, or TFAs, which are unsaturated fatty acids that have an unusual structure causing a range of health problems in the body.

Partially hydrogenated oils used for deep-frying are different from those used in baking, breading or candy coatings. Blends with different proportions of TFAs might be more spreadable, have an increased shelf life or have some other desired feature, but the advantages of these artificial fats are all on the manufacturer’s side of the equation. They provide no health benefits for the human body.

Due to their negative health effects, and the lack of any upside, the Food and Drug Administration began requiring trans fats to be declared on food labels. With the advent of having to reveal the number of grams per serving, food processors sought other methods to make their fats spreadable.

In one method, known as interesterification (IE), food processors use oils together with fully hydrogenated fats and create a mixture with the desired characteristics. It’s not something you can do at home with a measuring cup. This type of reconfiguration involves shuffling fatty acids around on triglycerides using enzymes or chemical catalysts. Many hydrogenated -- but trans fat-free -- shortenings on the market are made this way.

IE has been available to food processors for a while, but since it was less costly to keep using partial hydrogenation, and there was no public outcry for alternatives, it was not widely used until recently. Fully hydrogenated products made using IE can have zero trans fats -- or, from a regulatory standpoint, less than 0.5 grams of trans fats per serving, meaning “no trans fats” can be declared on the Nutrition Facts label.

While this new family of shortenings with no trans fats is a positive development, the jury is still out as to whether the use of IE fats might also give rise to health issues. There’s also the possibility that fats naturally high in saturates, such as palm oil and coconut oil -- or even fully hydrogenated oils -- used in blends might be the way to go. Tropical oils, long suffering from a public-relations black eye, have now gotten their green card.

As for whether they’re any better or worse in the kitchen, IE shortening products have undergone performance testing, so you can expect them to be functionally comparable to the older versions. Just as there are brand-to-brand variances with other ingredients, you may need to do some testing to find the shortening that works best with your recipes. But it would be prudent to keep IE fats to a minimum, given that we don’t have a complete picture on their impact on health.